The heart in mammals has four valves that regulate the direction of flow of blood through the four chambers of the heart.
The two atrioventricular valves which prevent the backflow from the ventricles of the heart into the atria and two semilunar valves which prevent backflow from the arteries into the ventricles.
The tricuspid valve is one of the atrioventricular valves and is situated on the right side of the heart between right atrium and the right ventricle. The healthy tricuspid valve generally has three leaflets, three papillary muscles and Chordae Tendineae.
In certain situations, the tricuspid valve can fail to operate partially, fully or at all in a patient. An unhealthy tricuspid valve can cause severe problems to the patient including death as a result of regurgitation of blood through the valve or other problems.
As a result, certain treatments have been developed to address problems with the tricuspid valve. For example in one type of treatment, tricuspid valve surgery, an artificial ring is inserted in to the heart to repair or restore the natural tricuspid valve function.
The natural tricuspid valve changes shape during the course of the cardiac cycle. The shape may be based on the contractions of the papillary muscles, the shape of the leaflets, the shape of the annulus, the supporting chordae and other factors. The tricuspid orifice shows large changes during the cardiac cycle and is easily dilated during the course of disease because of different factors.
The macroscopic structure of the heart may be described as a single muscular band that starts at the base of the pulmonary root and ends at the base of the aortic root. This band forms a basal loop that surrounds the tricuspid and mitral orifices and then descends toward the left ventricular apex in a spiral helix to form the apical loop. Contraction of the basal loop reduces the atrioventricular valve orifices. Therefore, the mobility and size of the tricuspid orifice are largely affected by the transversely oriented myocardial fibers, which surround the atrioventricular valves.
The tricuspid valve is rarely affected in a patient in isolation. Most often, the more prominent impact of other diseased valves minimizes the importance of correcting problems with the tricuspid valve. Since the valve is located near the entrance of the heart, its symptomatology is primarily axtracardiac and is often silent making detection and investigation more difficult. In addition, the tricuspid valve's behavior is closely related to the function of the right ventricle. In most cases, tricuspid regurgitation is secondary to right ventricular failure. The valve generally follows the dictates of the mitral valve, so resolution of the mitral problem is often followed by improvement in the degree of tricuspid regurgitation. For these reasons, cardiologists and surgeons often ignore or consider the tricuspid valve as secondary.
Diagnostic and surgical methods for treating functional tricuspid regurgitation have generally followed those applied to the mitral valve. However, the tricuspid valve has features which distinguish it from the mitral valve. It has a tendency to vary in degree following hemodynamic changes which makes evaluation difficult or unreliable.
There are a variety of known techniques for surgical intervention relating to tricuspid valve regurgitation and to restore the tricuspid annular dilation with varying degrees of success. The most common technique is the insertion of a tricuspid annuloplasty ring to help restore and reinforce the tricuspid annulus and consequently minimize the valve regurgitation. It is generally believed that matching the shape of the annuloplasty ring to the natural shape of the tricuspid valve is important to proper function of the ring. The relatively high recurrence rate of tricuspid regurgitation suggests that existing techniques are not fully satisfactory.
Any artificial ring should correspond closely to the shape and properties of the natural tricuspid valve. Recent studies showed high recurrence rate of severe tricuspid regurgitation in patients undergoing variety of tricuspid annuloplasties during mid-term follow up. These results question the efficacy of the current techniques of tricuspid repair.
A tricuspid valve ring is therefore desirable for repair of the tricuspid valve that corresponds closely with the natural valve.